Fluid reservoir



FIG. 1 is a perspective view as seen from the top, front and right side;

FIG. 2 is a top plan view;

FIG. 3 is a left side elevational view;

FIG. 4 is a rear elevational view;

FIG. 5 is a front elevational view; and,

FIG. 6 is a bottom plan view.

The ornamental design for a fluid reservoir, as shown and described.